The present combination invention relates in general to new, improved and more efficient apparatus for dehumidifying an air stream in conjunction with apparatus for simultaneously producing domestic hot water (hereinafter sometimes "DHW"), and more particularly to a combination ancillary heat pump (hereinafter sometimes "AHP") and multimodal evaporator coil system for such purpose.
In regard to domestic hot water production aspects of the present combination invention, experts within the electric utility industry have determined that the 1990 Federal Clean Air Act and other regulatory action may necessitate replacement of resistance electric heat water heating technology, due to the primary energy intensiveness of the operation of such technology. The Department of Energy report The Potential for Electricity-Efficiency Improvements in the U.S. Residential Sector, issued July, 1991, identifies the existing 22,000,000 residential electric hot water heaters as the largest single source of potential savings of electrical energy.
The above problems which are principally related to large levels of primary energy consumption have engendered the search for more energy efficient means of producing domestic hot water. Presently available systems for producing domestic hot water, include, inter alia, integrated and combined space conditioning and water heating heat pump apparatus, self-contained heat pump water heaters, desuperheaters and full condensers (some of which are provided as add-ons to condensing units), heat pipe dehumidification apparatus, and similarly related apparatus.
However, each of these presently available prior art methodologies has associated therewith one or more serious application and/or cost effectiveness problems. Some of the problems associated with the prior art are:
1. the necessity for protecting potable water lines from freezing with an add-on reclaim heat exchanger mounted within an outdoor (condensing) unit;
2. the major additional cost of providing a module with the compressor located indoors;
3. field modification of the refrigerant piping system; and
4. installation cost and application problems associated with dedicated heat pump hot water heaters.
In regard to dehumidification aspects of the present combination invention, air source heat pump water heaters can dehumidify the air inside a house, but such usages lower the operating efficiency. Moreover, such dehumidification is generally desireable in the summer but unnecessary in the winter. Accordingly, the dilemma is created as to whether this would be a greater benefit in optimizing the evaporator design for summer or winter.
in some preferred embodiments, a multi-speed blower could be used to change the heat pump water heater evaporating temperature, and thus the dehumidification capability of the system.
In view of the above difficulties, defects and deficiencies with prior art systems, it is a material object of the present invention to reduce significantly each of the above and other problems associated therewith.
It is a further object of the present invention to provide an ancillary heat pump and associated dehumidification system for production of domestic hot water wherein a preferably small and self-contained heat pump having a co-axial heat exchanger and compressor is disposed, in one preferred embodiment, with a heat exchanger coil thereof directly in the return air stream of a heat pump or of a heating and air conditioning system.
It is also an object of the present invention to provide means for injecting the associated cooling effect hereof directly into an accompanying heating and/or air conditioning system, rather than merely "dumping" such associated cooling effect into the space around the heater tank, while providing appropriate and efficient levels of dehumidification thereto.
It is also a further object of the present invention to provide apparatus wherein there is no necessity to pipe potable water into an outdoor environment, or, as an alternative, to repipe extensively the refrigeration circuit of the heat pump or condensing unit to an indoor heat exchanger location, but rather to keep the HVAC and hot water system refrigeration circuits totally isolated, so that there is no risk of water contaminating the HVAC refrigeration system in the event of a heat exchanger failure.
It is a yet further object of the present invention to provide hot water efficiently during the heating season regardless of the type of space heating fuel being used, and to provide appropriate and efficient levels of dehumidification thereto.
These and other objects of the ancillary heat pump and associated dehumidification apparatus for providing domestic hot water of the present invention will become more apparent to those skilled in the art upon review of the following summary of the invention, brief description of the drawing, detailed description of preferred embodiments, appended claims and accompanying drawing.